It is well known in the scroll compressor art to attach the fixed scroll to the rear head of the compressor by means of threaded fasteners. This method of attachment, however, often over time results in the loss of compressor efficiency due to leakage of the compressed fluid past the bolt holes, or failure of the compressor due to the deterioration of the scroll elements as a result of loosened bolts allowing the fixed scroll to separate from the rear head.
U.S. Pat. No. 4,815,952 to Hasegawa discloses a method for securing the fixed scroll into the rear head of a scroll compressor, utilizing bolts extending through holes in the end plate of the fixed scroll. It is furthermore disclosed that an optional bottom plate may be employed to cover the heads of the attaching bolts, to assist in preventing blow-by of the compressed fluid between the compression chamber and the discharge chamber. It is evident to one ordinarily skilled in the art, however, that the bolts may work themselves loose over time during operation of the compressor, thereby causing the disengagement of the optional bottom plate from the surface of the end plate as a result of contact between the bolt heads and the adjacent surface of the bottom plate. Thus, compressed fluid could pass between the compression chamber and the discharge chamber along the bolt holes through the end plate thereby reducing the efficiency of the compressor, and the bottom plate could be urged away from the end plate a sufficient distance to interfere with the operation of the orbiting scroll elements thereby causing the compressor to seize and fail. Moreover, in the disclosed alternative embodiment, which does not include a bottom plate, these same inefficiencies and failures could occur more quickly.
U.S. Pat. No. 4,547,138 to Mabe et al. likewise discloses a method for securing the fixed scroll into the rear head of a scroll compressor. Bolts extending through holes in the rear head are secured into threaded shanks formed on the end plate of the fixed scroll opposite the fixed scroll elements. As is evident to one ordinarily skilled in the art, these bolts may loosen over time during operation of the compressor, thereby allowing the fixed scroll to disengage from the rear head of the compressor. Thus, compressed fluid could escape from the discharge chamber to the atmosphere along the bolt holes through the rear head, and the fixed scroll could move away from its intended position adjacent the rear head causing interference with the operation of the orbiting scroll elements.
It would be desirable to provide a method for securing the fixed scroll into the rear head of a scroll compressor in a manner which would eliminate the potential for the compressed fluid to pass between the compression chamber and the discharge chamber, or from the compressor discharge chamber to the atmosphere.